[R-sig-Geo] get() in raster ?
Robert J. Hijmans
r.hijmans at gmail.com
Mon Nov 22 00:51:23 CET 2010
Hi Agus,
This is somewhat puzzling. The general approach works in this example:
r1 <- raster(nrow=10, ncol=10)
r1[] <- 1
r3 <- r2 <- r1
v <- list(r1, r2, r3)
do.call(stack, v)
# or simply:
s <- stack(v)
# or the more convoluted, if you have the object names rather than the
objects themselves:
v <- list(get("r1"), get("r2"), get("r3"))
s <- stack(v)
#And finally, if you want a brick (as you are dealing with large
files, I think it is more efficient to first make a stack and then
write the results to a brick):
b <- brick(s)
# Although in my example, this does also work:
b <- do.call(brick, v)
On Sun, Nov 21, 2010 at 10:22 AM, Agustin Lobo <alobolistas at gmail.com> wrote:
> Thanks Edzer, but neither work:
>> v = list("r1","r2","r3")
>> do.call(brick, v)
> Error in .rasterObjectFromFile(x, objecttype = "RasterBrick", ...) :
> file: r1 does not exist
> Calls: do.call ... <Anonymous> -> <Anonymous> -> .local -> .rasterObjectFromFile
Makes sense, because you are using character arguments, which are
interpreted as filenames.
>> v = list(r1, r2, r3)
>> bN = do.call(brick, v)
> Error in .rasterObjectFromFile(x, objecttype = "RasterBrick", ...) :
> file: r1r2r3 does not exist
Strange to have r1r2r3 concatenated.
> Calls: do.call ... <Anonymous> -> <Anonymous> -> .local -> .rasterObjectFromFile
> In addition: Warning messages:
> 1: In if (x == "" | x == ".") { :
> the condition has length > 1 and only the first element will be used
> 2: In if (fileext %in% c(".GRD", ".GRI")) { :
> the condition has length > 1 and only the first element will be used
> 3: In if (!file.exists(x)) { :
> the condition has length > 1 and only the first element will be used
> 4: In if (file.exists(grdfile) & file.exists(grifile)) { :
> the condition has length > 1 and only the first element will be used
>
> Also, in the real case the raster objects (i.e.,N1, N2 and N3) will
> not have values in memory, so I'm not
> positive that the list would be the way to go:
>
Should not matter
>> class(N1)
> [1] "RasterLayer"
> attr(,"package")
> [1] "raster"
>
>> inMemory(N1)
> [1] FALSE
>
>> v = list(N1, N2, N3)
>> bN = do.call(brick, v)
> Error in as.matrix(getValues(r)) :
> error in evaluating the argument 'x' in selecting a method for
> function 'as.matrix'
> Calls: do.call ... <Anonymous> -> addLayer -> addLayer -> .local -> as.matrix
This may be a real bug. But perhaps you can do
sN = brick( do.call(stack, v) )
>
> By now I'm editing the output of
> paste("N",1:360,sep="")
> for a call to brick() including the 360 raster objects. But there has
> to be an elegant way of doing this. Not a critical issue though.
>
> Agus
>
> 2010/11/20 Edzer Pebesma <edzer.pebesma at uni-muenster.de>:
>> Just pushed "send" too fast -- try without quotes to pass the objects
>> instead of their names:
>>
>> v = list(r1, r2, r3)
>> do.call(brick, v)
>>
>>
>> On 11/20/2010 11:51 AM, Agustin Lobo wrote:
>>> ok, the problem is that, as noted by Carson,
>>> I must use get("v") and not get(v).
>>>
>>> But still have problems to use get() within stack() or brick():
>>>> r1 = raster(SM[,,1])
>>>> r2 = raster(SM[,,2])
>>>> r3 = raster(SM[,,3])
>>>> v = c("r1","r2","r3")
>>>> get("v")
>>> [1] "r1" "r2" "r3"
>>>> bSM = brick(get(v))
>>> Error in .rasterObjectFromFile(x, objecttype = "RasterBrick", ...) :
>>> file: r1r2r3 does not exist
>>> Calls: brick -> brick -> .local -> .rasterObjectFromFile
>>>
>>> ( I'm trying to use get() because have to
>>> create a brick with 360 files that have been read as raster objects within
>>> a loop using assign() )
>>>
>>> Agus
>>>
>>>
>>> 2010/11/19 Robert J. Hijmans <r.hijmans at gmail.com>:
>>>> This suggest that you have an object "r1" that is a Raster* object.
>>>> Perhaps because of a saved session?
>>>> Have you looked at
>>>> ls()
>>>> Robert
>>>>
>>>> On Fri, Nov 19, 2010 at 1:24 PM, Agustin Lobo <alobolistas at gmail.com> wrote:
>>>>> Hi again!
>>>>>
>>>>> I'm having problems because cannot use get() from base once package
>>>>> raster has been installed:
>>>>>
>>>>>> v = c("r1","r2","r3")
>>>>>> v
>>>>> [1] "r1" "r2" "r3"
>>>>>> get(v)
>>>>> Loading required package: raster
>>>>> Loading required package: sp
>>>>> raster version 1.6-22 (17-November-2010)
>>>>> class : RasterLayer
>>>>> nrow : 18
>>>>> ncol : 36
>>>>> ncell : 648
>>>>> projection : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
>>>>> xmin : -180
>>>>> xmax : 180
>>>>> ymin : -90
>>>>> ymax : 90
>>>>> xres : 10
>>>>> yres : 10
>>>>>
>>>>> Even not having loaded raster, it gets automatically loaded once I
>>>>> call get(). Is this a bug?
>>>>> In general, is there a way to force that, in case of conflict, you run
>>>>> a particular function from a given package?
>>>>>
>>>>> Thanks!
>>>>>
>>>>> Agus
>>>>>
>>>>
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>>>
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>>
>> --
>> Edzer Pebesma
>> Institute for Geoinformatics (ifgi), University of Münster
>> Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
>> 8333081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de
>> http://www.52north.org/geostatistics e.pebesma at wwu.de
>>
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